The Norwegian Mother and Child Cohort Study (MoBa) is an ongoing prebirth cohort study. Enrollment was completed in 2008 resulting in 106,980 pregnancies in the study. The study is based on questionnaires completed by the mother and father, and biological specimens are collected from the mother, father and child. The main purpose of the study is to find causes of diseases. NIEHS is providing partial support for the study, and in 2002 expanded the data collection protocol to include collection of more biologic specimens from the mothers during the 17th week of pregnancy (additional serum, a specimen of whole blood collected in a trace-element free container, and urine). These specimens will enhance the ability to examine the relation of environmental exposures in relation to various health outcomes in the children and their mothers. As of April 30, 2009, 77,104 subjects had provided blood and urine that was collected in conjunction with NIEHS. We added to the MoBa protocol the collection additional urine specimens in pregnancy, at weeks 23 and 29, for a subset of women. 690 women have a complete set of three urine specimens from pregnancy. This year the laboratory work was completed for a study in which we attempted to measure the levels of metabolites of organophosphate pesticides and bisphenol A in these specimens, to determine how reproducibile the levels were. We have learned that the preservative used in the collection of the urine specimens contaminated them with free bisphenol A, and makes the specimens difficult to analyze for organophosphate pesticide metabolites. This information will be of great use as we plan future studies. Future studies seeking to quantitate bisphenol A will need to measure total and free BPA, so that conjuated BPA can be estimated. Special new studies will be needed to see if the specimens can be analyzed for organophosphate pesticide metabolites, because the standard approach will not work. We published one paper reporting the contamination, and have identified two laboratories that will work with the urine specimens to see if they can analyze them for organophosphate pesticide metabolites and phthalates. We also have studied the plasma concentration of perfluoralkyl substances in relation to various outcomes among women in the MoBa cohort. This year we published one paper on the determinants of plasma levels of these compounds. We are completing a series of other papers based on our data on plasma levels of the compounds; one is on preeclampsia, two are on values of clinical chemistry parameters in relation to perfluorinated compound levels, and one, using the same group of women, is about physical activity in pregnancy and plasma levels of C-reactive protein, a marker of inflammation. We are planning a series of new studies, using the data in hand, to examine a) the reliability of the plasma levels over a period of several years, b) exposure in relation to child growth, and c) exposure in relation to infections in childhood. Because of our interest in perfluoroalkyl substances, we have also been collaborating on studies of the pharmacokinetics of these compounds, which provide insight into epidemiologic findings. We published one paper on the pharmacokinetics of these compounds in the past year. Scientists at NIEHS are developing several studies that will be nested within MoBa. A list of the studies currently planned includes: Risk factors for cerebral palsy, A Search for the Non-mendelian Transmission of Human Genes, Dietary Intake and Gestational Diabetes, Physical Activity in Pregnancy and Infant Neurodevelopment, Organophosphate Pesticide Exposure and Risk of Autism, and additional studies on perfluorinated compound exposure and health.